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AIXpert Blog

SOBRE ESTE BLOG

AIXpert Blog is about the AIX operating system from IBM running on POWER based machines called Power Systems and software related to it like PowerVM for virtualisation, PowerVC for Deploying VM's and PowerSC for security plus performance monitoring and nmon

This is a follow on from yesterdays blog due to Chris Gibson highlighting a question/concern from one of his customers in Australia.They were comparing Power6 and Power7 and the utilisation numbers from the SMT Logical Processors and the graphs look different. I looked at some nmon data (what else!) and yes they are looking different and then I ran a simple generated workload test and duplicated the graphs. Below I then explain them - once again these are my personal observations rather than an official AIX developers insider statement. I... [More]

Before we look further in to memory affinity we need to recap on the scheduling of processes and process threads of a multi-threaded process to simultaneous multi-threading (SMT) processors like POWER7. POWER5 and POWER6 had two modes of SMT off (one thread) and on (two threads) - with SMT=on two processes run at the same time (in the same clock cycle) on the CPU-core but using the different logical units inside of the CPU-core (units like the integer maths (there is more than one), floating point maths (there is more than one), compare and... [More]